The present invention relates generally to adaptive optics systems, and more specifically to a wavefront sensor system which may be used for real time sensing of optical wavefronts.
Light beams, which are sensed by optical detectors, are subject to distortion from a number of sources. These sources of distortion include both the atmosphere and the optical elements of the optical detectors themselves.
The task of eliminating distortion of sensed wavefronts is alleviated to some extent by the systems disclosed in the following U.S. Patents, the disclosures of which are incorporated herein by reference:
U.S. Pat. No. 4,141,652 issued to Feinleib; PA1 U.S. Pat. No. 4,399,356 issued to Feinleib et al; and PA1 U.S. Pat. No. 4,490,039 issued to Bruckler et al.
In the apparatus of U.S. Pat. No. 4,141,652, a modulated reference beam from a laser is combined with an incoming beam of light. The combined beam is then processed into a detectable AC signal and divided into a plurality of beams by subaperture dividing components and is detected by an array of photodetector cells for measuring the position of both the focused incoming beam and the reference beam. The difference between the relative position of the incoming beam and the reference beam is indicative of the distortion in the system and is used to provide a signal to compensate for such distortion.
The system of U.S. Pat. No. 4,399,356 employs an image divider divided in "N" segments ("N"&gt;1) which are focused on "N" detector arrays and detected by "S" detectors in the "N" detector arrays. Like the system of the Feinleib et al `652` reference, the detected signals are used to produce a signal proportional to the tilt of the wavefront to correct distortions in the wavefront. The Feinleib et al `356` reference divides the combined beam into multiple segments for the detector arrays using a prism. Each individual detector array measures a localized tilt of the incoming beam to provide a signal that may be used to correct the distortions of the incoming beam.
The Bruckler et al reference discloses the use of a large number of photosensitive elements for locating more accurately source and reference beam spots. The centroid of each source beam spot from each sub-front of the reference beam is computed by an algorithm to yield a measure of the degree of source beam aberration. While the system of Bruckler et al is instructive, it does not seem to provide for continuous calibration and correction of wavefront distortions.
In view of the foregoing discussion, it is apparent that there currently exists a need for a wavefront sensor system which continuously measures the distortions of sensed wavefronts, and which senses the localized tilt of sensed wavefronts, so that the optical distortion of the original wavefront can be removed. The present invention is intended to satisfy that need.